Alteration of L-proline oxidase activity of sarcosine oxidase and a structural interpretation

Sarcosine oxidase (EC 1.5.3.1; sarcosine:oxygen oxidoreductase [demethylating]) is a flavoprotein that catalyses the oxidative demethylation of sarcosine to yield glycine, formaldehydethe, and hydrogen peroxide. This enzyme is involved in the bacterial metabolism of creatinine with the related enzymes, creatininase and creatinase. It is industrially important and is used with creatininase and creatinase for the enzymatic assay of creatinine in clinical settings . Recently, the metabolite sarcosine has been identified as a potential urine-based biomarker for prostate cancer progression. Sarcosine oxidase might prove useful in the determination of prostate cancer. We have previously screened a sarcosine oxidase from the genus Arthrobacter (SoxA) and cloned the soxA gene. We have also altered the substrate specificity and optimum pH of SoxA by random and sitedirected mutagenesis, and succeeded in active-site analysis and stabilization of this enzyme by the substitution of cysteine residues. The wild-type and stable Journal of Analytical Bio-Science Vol. 33, No 2 (2010)